Effect of Different Copper Formulations Tank-Mixed with Fenbutatin-Oxide for Control of Citrus Rust Mites (Acari: Eriophyidae) on Florida Citrus

Abstract

One or more rates of fenbutatin-oxide (= Vendex®) 4 L applied alone were compared with the same rates of Vendex tank-mixed with one or more formulations of copper and an untreated check for control of citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae), in 4 citrus grove sites between 1988 and 1991. The copper formulations corresponded to recommended rates in the Florida Citrus Spray Guide and included: 99% GC basic copper sulfate (pentahydrate) with 53% metallic copper, a 77% WP copper hydroxide formulation containing 50% metallic copper and a 61.4% copper hydroxide DF formulation containing 40% metallic copper. Reduced effectiveness of Vendex occurred when combined with all 3 copper formulations. Both copper hydroxide formulations were more disruptive in reducing the effectiveness of Vendex in controlling citrus rust mite compared with the basic copper sulfate formulation. Increases in citrus rust mite numbers occurred in the copper-only treatments in 2 of the 3 field experiments. In both instances, population increases in the copper-only treatments occurred at the same time as those in the untreated check trees, suggesting a stimulatory effect by the copper compounds.